I've been a user of wireless networks almost since they arrived on the PC scene. They're not my preferred way of connecting because they're never as reliable as a wired connection. But you can't beat them for giving you the option to turn almost any location into a workspace.

But I've never had a more difficult time connecting to one than the incident I encountered recently while traveling in Scotland. I spent many hours trying to get connected to a wireless network that three others had no trouble with. Eventually I discovered the secret, and I learned something new from that experience that you may need to know some day.

Wireless disconnectivity

I was traveling with several others, and between us we had five laptops-two Macbooks, two Windows 7 laptops, and a Windows XP laptop. Both Macs could see and connect to the network fine. One of the two Windows 7 laptops could connect fine. But one of the Windows 7 laptops and the XP laptop could not connect at all. The network was from a Virgin Mobile wireless N access point which also did duty as the router. It did not broadcast its signal. We checked the troubled laptops a dozen times to make sure we all had the same settings-SSID, WPA2-PSK, passphrase, AES encryption, connect even if signal not broadcast. Nothing worked.

After going through the exercise of checking and rechecking all of the variables, and trying and retrying to connect, we went through the mental exercise of eliminating possibilities. It couldn't be the credentials or network settings, as they were the same on all laptops. It couldn't be a purely-XP issue, since one of the Win 7 laptops also couldn't connect. It couldn't be the wireless protocol we were using, since the two Win 7 laptops were configured identically, and the XP laptop was using a D-Link DWA-131 Wireless N USB Adapter, making it the most up-to-date adapter in the bunch (ironically enough). It couldn't be an incompatibility with Windows 7, since one of the Win 7 laptops had no difficulty.

With all those variables ruled out, we turned our attention to the only remaining possibility we could think of: The wireless adapter's advanced settings. I have turned to this possibility hundreds of times before on many different machines-usually as a last resort, and usually finding nothing useful there. But after hours of getting nowhere trying everything else, we had nothing to lose.

I opened up the dialog on the XP laptop's D-Link adapter and reviewed the options, and as soon as I did I got suspicious. There was an option for 802.11d, with Enable and Disable options. It was set to its default, Disable. What on earth is 802.11d? I didn't know. I had never heard of it before. I was well acquainted with 802.11a, b, g, and n, but not d. I changed the setting to Enabled-as skeptical that it would make a difference as I was suspicious that it might-and then closed the dialog and waited.

Moments later, the tray icon reported that the wireless connection was acquiring an IP address, and just seconds after that, the laptop was connected. That turned out to be the secret-I was able to connect to the network the rest of the week.

802.11d to the Rescue

What exactly is 802.11d? I'm not a networking expert, but you will find a Wikipedia article on the subject, and the official IEEE specification is available at http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=946610. As I understand it, 802.11d simply defines a set of regulatory domains beyond the six defined in the original 802.11 standard-and that apparently includes Scotland. That is, there are geopolitical regions not covered by 802.11, and if you want to connect to a network in one of them, your adapter needs to support 802.11d.

In any event, 802.11d is the ticket. Upon further investigation, I found that the one Win 7 laptop that couldn't connect was a slightly older model whose wireless adapter did not support 802.11d, and there are no driver updates available for it, so that machine was as blind as the XP without a newer adapter. Whenever we wanted to connect that laptop to the network, we had to install the D-Link DWA-131 adapter first, just as we did with the XP machine.

As for the other laptops, I can only assume that they had newer adapters with newer drivers, drivers that more intelligently went searching for 802.11d when needed.

I am guessing that other USB wireless N adapters can do what the D-Link DWA-131 can do, but I don't have a testing lab to find out, so I can't be sure. In the absence of having that knowledge, you may want to get one and throw it into your laptop bag, just in case, if you have any doubt that your wireless adapter supports 802.11d. At the very least, it will give you another set of options if you find you are simply unable to connect to a wireless network that you can't fiddle with.

I won't go over the steps of installing the D-Link DWA-131 Wireless N USB Adapter, because the adapter itself comes with the appropriate instructions and software for doing that. But I will tell you how to enable 802.11d connectivity using the D-Link. The steps are the same for Windows XP, Windows Vista, and Windows 7. Using screen shots from XP, here are the steps:

Figure A

2. Right-click over the connection associated with the D-Link adapter and choose Properties.

Figure B

3. You should see the Properties dialog for the wireless connection. Choose Configure:

Figure C

4. You should see the Properties dialog for the wireless adapter. Choose the Advanced tab:

Figure D

5. Change the Value to Enable, and then click OK:

Figure E

That should do it. Give your wireless adapter a few moments to start negotiating a connection with the new protocol and you should be good to go.

Conclusion

If you rely on wireless networks and travel internationally, you may find yourself in need of 802.11d support some day. For laptops not already so equipped, the D-Link DWA-131 can fill the bill. It's small, cheap (you can get one for about $25), fast, and reliable. Not bad for a wireless network silver bullet.